Vibrating and other separatory screen assemblies are generally known in the art and are very useful in accomplishing the separation of materials, on the basis of the size of the materials to be separated. A slurry of liquid and entrained solids can be caused to run or to flow across an upper surface of a screen panel assembly. Particles of at least a certain size will not pass through apertures in the screen panels and will thus be separated out of the slurry. The screen panel assembly is caused to vibrate by a suitable vibratory drive, with this vibratory motion being beneficial in facilitating the proper separation of the slurry which is directed onto the screen panel.
One such vibrating separatory screen panel assembly is shown in U.S. Pat. Nos. 5,112,475 and 5,277,319, both to Henry, and both assigned to Conn-Weld Industries, the assignee of the present application. In those two patents, there is disclosed a screen panel mounting system for a vibrating screen assembly. There is also disclosed a screen panel which is securable in the vibrating screen assembly by using the panel mountings system. A plurality of screen panels are secured to a panel deck of a frame portion of a vibrating screen assembly. A plurality of elongated hold downs or center retainers, which are made of a resilient elastomeric material, such as polyurethane, are provided with integral spaced anchoring pins along their bottom surface. Those integral, spaced anchoring pins are receivable in apertures in an anchor member. Once the hold down members or center retainers have been secured to the anchor member, which is, in turn, attached to spaced cross members or tubes of the frame of the vibratory separator, the screen panels are placed atop the panel deck with their side edges in contact with the center retainers. Elongated key members are inserted into upwardly facing slots in the center retainers to spread wing portions of the retainers laterally outwardly. This spreading of the wings of the center retainers causes the wings to grip the side edges of the screen panels so that these panels are secured in the vibrating screen assembly.
The panel mounting system, which is disclosed in the two above-referenced Henry patents utilizes screen panels and cooperating anchor members which must be bolted, welded or otherwise secured to cross members of the panel deck of the vibrating screen assembly. An owner of a prior art vibrating screen apparatus, which is not provide with the appropriate anchor members disclosed in the prior Henry patents, must make substantial revisions and modifications to his vibrating screen assembly if he is to be able to enjoy the advantages of the Conn-Weld Industries panel mounting system.
A center retainer assembly for a panel mounting system is disclosed in U.S. Pat. No. 5,398,817 to Connolly et al, which is also assigned to Conn-Weld Industries. The center retainer assembly described in the '817 patent utilizes an elongated bolting bar which is encased in a resilient material and which includes an elongated center retainer. The center retainer assembly of this patent is placed into an upwardly facing retainer channel and is secured to the retainer channel by placement of the bolts carried by the bolting bar through holes in the retainer channel. The retainer channel is, in turn, secured to mounting plates that are attached to a cross tube or to a cross bar of a vibrating screen assembly.
A more recent screen panel retainer system is described in U.S. Pat. No. 6,964.341 to Bacho, et al. That patent is also assigned to Conn-Weld Industries, the assignee of the subject patent application. In that system, the screen panels are held in place by screen panel edge strips which have pockets on their under surfaces. Those pockets are cooperatively shaped to receive a plurality of ears that are situated on upper surfaces of retainer bars. Those retainer bars are connected to the underlying screen stringer rails.
A snap lock separating panel and retainer system is disclosed in U.S. patent application Ser. No. 11/798,537; filed May 15,2007 in the name of the inventors of the subject patent application, now U.S. Pat. No. 7,717,869, issued May 18,2010, and also assigned to Conn-Weld Industries, Inc. In that application there is disclosed a snap lock separating panel retainer system as well as a separating panel which is usable with the retainer system. Elongated locking strips are used to engage locking profiles on the separating screen panels. Those locking strips utilize under cut receptacles to receive enlarged heads of retainer pins that are formed integrally with center retainer strips. Those center retainer strips are, in turn, secured to the screen stringer rails that are typically provided in vibrating separatory machines. The locking strips are snap locked onto the center retainer by the engagement of the enlarged heads of the retainer pins in the cooperatively shaped undercut receptacles in the locking strips.
The various screen panel retainer systems, as described and depicted in the several Conn-Weld Industries patents and applications discussed above, have all enjoyed some degree of success in the industry. However, each has its individual limitations which have made each system less than suitable for use in all equipment, regardless of manufacturer and configuration. Several of the earlier systems required modification or reworking of the industry standard screen stringer rails. Others, such as the system described in the Bacho et al U.S. Pat. No. 6,964,341 have been found somewhat difficult to use and have required the provision of screen panel edge strips that have had to be field-installed on the replacement screen panels. Adjacent screen panels have sometimes required the use of cooperating and abutting screen panel edge strips. The abutment and alignment of these screen panel edge strips has been somewhat difficult to obtain in the field. This has increased the time that is required to both initially install the prior systems and to then replace worn screen panels with replacement screen panels. When a machine, which is operating in an industrial setting, must be taken out of service for repair or replacement of essential elements, that is a loss of that machine's production capacity. Such losses need to be kept at a minimum.
Several of the prior screen panel securement arrangements, in addition to their requirement of special screen panel edge strips, have required numerous parts and have been expensive to make and install. As discussed above, when a production machine is taken out of service, money is lost. It is this imperative that the screen panel retainer system be relatively simple, having a limited number of components, that is be quick and easy in its installation, and universal in its ability to adapt to all of the various vibrating separating machines that are used in the industry. Those various machines typically utilize screen stringer rails that are secured atop cross tubes which are frame components of the vibrating separatory machines. The screen stringer rails are typically 2″×2″ hollow steel tubes and are provided with mounting holes spaced along an upper surface of each such screen stringer rail at a spacing distance of 4″. This industry standard configuration must serve as the basis for the configuration of the screen center panel retainer system.
A vibrating separating machine uses an array of screen panels to separate solid materials from a slurry. The screen panels are situated in an array that typically utilizes a plurality of screens abutting each other, or adjacent to each other both in a direction of material flow and also in a direction the is traverse to the material flow direction. It is the exposed surface area of these screen panels which accomplishes the material separation. The greater the amount of exposed screen surface, the greater capacity for material separation the machine will have. In the prior systems, the retainer structures have tended to cover over substantial portions of the sides or edges of adjacent ones of the screen panels. While that reduction in available screen surface area may amount to only 5% of the total screen surface area, that is still 5% of the total screen surface area which is no longer available for accomplishing the machine's primary objective of separation of solids from a slurry. Any increase in open screen area will improve the operating characteristics of the vibrating separatory machine that uses the screen panel center retainer system of the present invention.
Many of the prior screen panels utilize cross dams and dam retainers. The ends of the lock strips in prior systems have abutted the ends of the dam retainers. Temperature changes may cause the length of the lock strips to change. This will either lead to an interference between the ends of the lock strips and the cooperating pieces of the dam retainers or will form a gap that may let particles pass through.
It will thus be understood that a need exists for a screen panel retainer system which overcomes the limitations of the prior systems, which uses a minimum number of panels, which is easily installed and operable, which is adaptable to various screen stringer rails and which provides an increase in open screen area. The screen panel center retainer system, in accordance with the present invention, overcomes the limitations of prior art and is a substantial advantage over the presently available systems,